Draft control device



- July 27, 1954 l. M. BITHER DRAFT CONTROL DEVICE Filed July 7, 1950 F|G.5 v

INVENTOR. ISAIAH MORRIS BITHER FIG.4

ATTQRNEY Patented July 27, 1954 UNITED STATES ATENT OFFICE 2 Claims. 1

My present invention relates to fuel economizers and more particularly to a novel device for reducing the fuel consumption of a furnace.

The principal object of the present invention is to provide a device for reducing the fuel consumption of the furnace by retarding the rate of flow of warm air and combustion gases in the smokestack.

Another object of the present invention is to provide a device of the character described which will not choke off the furnace in the event of a sudden surge caused by puffing explosions of the oil burner.

Another object of the present invention is to provide a device of the character described which is simple in construction and easy and economical to manufacture and install.

With the above and other objects and advantageous features in View, my present invention consists of a novel arrangement of parts more fully disclosed in the detailed description following, in conjunction with the accompanying drawings, and more particularly defined in the appended claims.

In the drawings,

Fig. 1 is a section of a horizontal smokestack showing my device installed therein.

Fig. 2 is .a section taken on line 2-2 on Fig. 1.

Fig. 3 is a section taken on line 33 on Fig. 1.

Fig. 4 is a section of a vertical smokestack showing my device installed therein.

Fig. 5 is a view similar to- Fig. 4 showing the action of the device in the case of a puff or explosion in the furnace.

Various devices have been constructed for lowering the fuel consumption of a furnace, particularly an oil burning furnace, by retarding the flow of hot air from the furnace up the smokestack. This will permit the furnace to extract a larger quantity of heat from the hot .air before it is dissipated up the smokestack. Such devices employ various means such as thermostatic coils for interposing a baffle in the smokestack when the stack temperature reaches a certain height. While such devices actually operate to reduce fuel consumption, I have found that they are slow in operation and not as efficient as such a device should be.

In my present invention, I have provided a simple device for retarding the air flow, without interfering with the chimney draft. The retarding elements are constantly in position and the hot gases are slowed down so that a maximum amount of heat is extracted therefrom by the boiler. The device of the present invention can readily be applied either to horizontal or vertical stack constructions.

Referring more in detail to the drawings illustrating my invention, Figs. 1-3 inclusive illustrate the device incorporated in a horizontal installation. The device is installed in the smokestack If! leading from the furnace to the chimney. It comprises a set of three baffie plates II, I2 and i3 suspended vertically in spaced relationship in the stack Ill. The central plate I2 comprises a flat annular ring portion, as shown in Fig. 3, having a comparatively large central opening I4. At opposite vertical portions of the plate I2 are rectangular slots I5 and I6 adjacent the central opening It, for a purpose hereinafter to be described. The plates II and I3 are identical and each comprises an annular disc, as shown in Fig. 2, of slightly larger diameter than the central opening I4 in the plate I2. The plates II and I3 are each provided with oppositely disposed vertically aligned rectangular openings IT and 18 adjacent the periphery thereof, as shown in Fig. 2.

To retard the flow of hot gases through the stack ID, the plates II, I2 and I3 are suspended in the center of the stack in spaced relation with the plates II and I3 on either side of the plate I2, as shown in Fig. 1. As the hot gases pass through thestack it, they will first hit the plate II or I3, depending on the location of the furnace, and will be forced to travel around the plate I3. They will then meet the larger diameter of the plate l2 and be turned inwardly through the center opening I4 thereof. They will then meet the flat surface of the plate II or I3 and be forced around that. This forces the furnace gases through a circuitous path, thus retarding its rate of flow without interfering with the chimney draft. To make sure that the furnace is not blocked in case of sudden puffs or back drafts, the plates tl, I2 and I3 are suspended through the openings IT in the plates II and I3 and the opening IS in the plate I2, so that they will swing freely with the pull of the draft.

While any type of suspension device may be employed, I prefer to use the suspension device shown in Fig. 1. I provide a bar or strap I9 which passes through the openings I! in the plates II and I3 and into a slot 20 beneath the opening I5 in the plate I2. The ends of the bar or strap I9 are turned upwardly as at 2! and are bolted to a pair of L-shaped supports 22 which are in turn bolted to the top of the stack ID, as shown in Fig. 1. To retain the plates II, l2 and I3 in proper spaced relationship without interfering with the swinging action thereof, I

provide strap members 23 which comprise inverted U-shaped portions 24 terminating at one end with an integral fiat portion 25. The flat portion 25 is bolted to the bar d9, as shown in Fig. 1, and the inverted U-shaped portion 24 passes over the top edge of the plates H and I3 and through the opening 15 of the plate I2 to lock each plate to its position along the bar It.

The above construction must be varied as to the spacing and size of the various plates for different sizes of stacks. For example, I prefer that the plates H, l2 and [3 be made out of sheet steel one-sixteenth inch thick. In a smokestack having an eight inch diameter, the plates H and i3 should be approximately five and oneeighth inches in diameter and the plate l2 should be approximately six and three quarters inches in diameter. The central opening of the plate 2 is approximately four and one-eighth inches in diameter. With the above sizes and constructions, the plates ll, i2 and I3 should be approximately two and one-sixth inches apart from each other. While these sizes may be varied, I have found that they produce a maximum efficiency in the saving of fuel.

To install the economizer, it should be positioncd as close to the furnace in the stack as is conveniently possible. In a standard oil burner installation, a furnace relay switch is usually positioned either at the furnace or in the stack adjacent the furnace. The economizer should be positioned next in line in the stack, as close to the relay as possible without interfering with the operation thereof. I have found that with such an installation a considerable amount of fuel is saved. The plates ll, l2 and I3 retard the fiow of the hot gases and, of course, get extremely not themselves. The temperature of the smokestack on the furnace side of the device will be much higher than on the chimney side, indicating that the device is operating properly. This drop in temperature between the furnace and the stack should be from 12-28%, and the resultant economy in fuel consumption should be at least ten percent.

Where the stack Iii extends vertically from the furnace, the consiruction shown in Figs. 4 and 5 must be used. In this construction, the plates i i, 12 and it are attached to the strap or bar is by the members 23 similarly to the construction shown in Fig. 1. The ends 2! of the strap or bar 19 are bolted to the L-shaped members 22 which are in turn bolted to one side of the stack It now in vertical position. To retain the plates ii, [2 and i3 in horizontal position in the stack, I provide a second bar or strap 26 which passes through the lower openings 18 in the plates H and i3 and through a slot 2? adjacent the lower opening it in the plate l2). The plates II, [2 and I3 are pivotally held in parallel spaced relationship by the members 28 on the bar 26 which are identical with the members 23 on the bar [9. This construction would normally allow the plates to swing downwardly into the stack. However, note that the plate I2 is of larger diameter than the plates H and i3. I, therefore, provide an L-shaped stop member 29 which is bolted to the stack is at a point opposite the strap 19, the horizontal portion of the member 29 extending into the path of movement of the plate I2 so that the edge of the plate !2 rests thereon as shown in Fig. 4. Inasmuch as the bars 19 and 26 and the members 23 and 28 lock the plates in spaced parallel relationship, the member 29 retains all the plates in the position shown in Fig. 4. If desired, additional L-shaped members 29 may be positioned circumferentially about the edge of the plate 52 for additional support, or a single elongated L-shaped strip may be employed. With the parts positioned as shown in Fig. 4, the member 29 will prevent the plates from swinging downwardly into the stack, but will permit upward movement of the plates into the position shown in Fig. 5, should there be a puff or small explosion in the furnace. This construction is necessary for safety, as a fixed baiile may result in breakage in the case of such minor puffs or explosions. The operation of the vertically positioned device shown in Figs. 4 and 5 is similar to the operation of the horizontal device shown in Fig. l. The device is extremely simple to manufacture and assemble and economical to install. The size and spacing of the plates and the method of suspension may, of course, be varied to suit the requirements of different stack constructions.

While I have described a specific embodiment of my invention, it is obvious that changes may readily be made in the size, shape or relative arrangement of parts, without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A draft retarder for a furnace fiue comprising' a tubular stack, three bailie plates positioned in spaced relation in said stack at right angles to the axis of said stack, said plates being of smaller diameter than said stack, the center plate being of a large diameter and having a large central opening and the end plates being of smaller diameter than said center plate but of larger diameter than said center plate opening, and hinge means connecting each plate adjacent one peripheral edge thereof to said stack in aligned relationship and permitting free swinging movement of the opposite ends of said plates in said stack.

2. A draft retarder for a furnace flue comprising a vertical tubular stack, three baiiie plates positioned in spaced parallel relation in said stack at right angles to the axis of said stack, said plates being of smaller diameter than said stack, the center plate being of a large diameter and having a large central opening and the end plates being of smaller diameter than said center plate but of larger diameter than said center plate opening, hinge means connecting each plate adjacent one peripheral edge thereof to said stack in aligned relationship and permitting free swinging movement of the opposite ends of said plates in said stack, said opposite ends being hingedly connecting to a spacing bar to retain said plates in parallel relation in any swinging position in said stack, and stop means operatively associated with said stack and said plates preventing swinging movement of said plates from a horizontal position downwardly in said stack but permitting swinging movement upwardly in said stack.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 74,520 Dowe Feb. 18, 1868 172,914 Culveyhouse Feb. 1, 1874 175,166 Rhamy Mar. 21, 1876 1,034,507 Powers Aug. 6, 1912 1,272,064 Lezius July 9, 1918 2,130,491 Gilliland Sept. 20, 1938 2,262,252 Roland Nov. 11, 1941 

